The present invention relates to the field of electronic devices in general, and more particularly, to pin limited electronic devices.
Many electronic devices, such as radiotelephones, use a battery to provide power thereto. For example, power may be provided to a radiotelephone by an attached battery. Information associated with the battery, such as temperature and the battery type, may enable improved performance of the battery.
It is known to include an Identifier (ID) in the battery so that the type of the battery may be determined. Some batteries include resistors across which voltage levels can be developed to detect the ID of the battery. For example, the ID may identify the battery as a nickel-cadmium type battery. Accordingly, a radiotelephone to which the battery is coupled may use a set of nickel cadmium battery parameters to more accurately predict the state of the battery.
It is also known to monitor the temperature of a battery using thermistors in the battery. Monitoring the battery temperature may enable the radiotelephone to charge the battery at the proper rate, provide the proper charge termination, and reduce the likelihood of damaging the battery due to overheating during recharging. The thermistor typically provides a resistance which is inversely proportional to the temperature of the battery. Accordingly, the voltage level developed across the thermistor can indicate the temperature of the battery.
Unfortunately, using resistors and thermistors to indicate the type and temperature of the battery may limit the number of battery types that can be accurately identified. For example, it is known to connect a thermistor in series with an ID resistor in a battery. The thermistor may, for example, provide a resistance of 1K ohms to 1M ohms in response to variations in the temperature of the battery. If the ID resistor has a resistance value of about 1K ohms, the total resistance of the thermistor and the ID resistor can vary between 2K ohms to 1.002 M ohms. Accordingly, it may be difficult to accurately distinguish between more than a few battery types using different ID resistor values.
It is also known to use processors, such as single chip microcomputers, in a battery to identify the type of the battery and determine the temperature. For example, a processor may be programmed with a code to identify the battery type and be coupled to a temperature sensor to determine the temperature. The processor may then serially transmit the ID and temperature information to the electronic device (such as a radiotelephone) via a pin on the battery that electrically contacts the electronic device. Unfortunately, processors may be expensive relative to the techniques discussed above. Accordingly, there is a need for improved circuits, batteries, user terminals and methods that provide information associated with input/output in limited devices such as batteries.
It is, therefore, an object of the present invention to allow improved circuits and methods that provide information associated with input/output pin limited electronic devices.
It is also an object of the present invention to allow a reduction in the cost of providing information associated with input/output pin limited electronic devices.
It is a further object of the present invention to allow improved battery devices.
These, and other objects of the present invention, may be provided by an information circuit that includes an input/output pin electrically coupled to a first circuit path and a reference pin of the device. The first circuit path is responsive to a first excitation on the input/output pin, wherein the first circuit path includes a first component device responsive to a first characteristic of the input/output pin limited device. A second circuit path is electrically coupled between the input/output pin and the reference pin and is responsive to a second excitation on the input/output pin, wherein the second circuit path includes a second component device responsive to a second characteristic of the input/output pin limited device.
Accordingly, the present invention allows information associated with the input/output pin limited device to be transmitted via a single input/output pin, thereby allowing a reduction in the cost of determining the information. For example, the first excitation can be applied at a first frequency and the second excitation can be applied at a second frequency. Respective responses to the first excitation can identify first information associated with the input/output pin limited device and the response to the second excitation can identify second information associated with the input/output pin limited device. In one embodiment, the first excitation is an AC signal and the second excitation is a DC signal.
In another aspect of the present invention, the first component device has a first impedance associated with the first characteristic and the second component device has a second impedance associated with the second characteristic.
In another aspect of the present invention, the first characteristic is a type of input/output pin limited device and the first component device is a resistor having a selected resistance associated with the type of input/output pin limited device.
A user terminal according to the present invention includes a user terminal input/output pin. A first excitation circuit is electrically coupled to the user terminal input/output pin and generates a first excitation at a first frequency at the user terminal input/output pin. A second excitation circuit is electrically coupled to the user terminal input/output pin and generates a second excitation at a second frequency at the user terminal input/output pin. A response measurement circuit is electrically coupled to the user terminal input/output pin and measures respective first and second responses to the first and second excitations at the user terminal input/output pin.
In still another aspect of the present invention, the user terminal includes a battery device and a battery device reference pin. A battery device input/output pin electrically couples the battery device to the first and second excitation circuits and the response measurement circuit via the user terminal input/output pin, wherein a user terminal input/output pin is configured to be coupled to the battery device input/output pin.
In another aspect of the present invention, the user terminal includes a battery device housing wherein the battery device is positioned within the battery device housing and the battery device input/output pin is positioned on the battery device housing so as to electrically couple to the user terminal input/output pin. A user terminal housing wherein the first and second excitation circuits and the response measurement circuit are positioned in the user terminal housing and wherein the user terminal input/output pin is positioned in the user terminal housing so as to electrically couple to the battery device input/output pin.
A method according to the present invention includes applying a first excitation at a first frequency to an input/output pin of the battery device. Measuring a first response to the first excitation at the input/output pin of the battery device and then applying a second excitation at a second frequency to the input/output pin. Measuring a second response to the second excitation at the input/output pin.
A battery device according to the present invention includes an input/output pin and a battery information circuit. The battery information circuit includes a means for providing first information associated with the battery device to the input/output pin in response to a first excitation applied to an input/output pin of the battery device at a first frequency and a means for providing second information associated with the battery device to the input/output pin in response to a second excitation applied to the input/output pin at a second frequency.